The present invention relates to an image forming apparatus constituting a transport path that transports paper fed from a feeding portion to a discharge portion via an image forming portion, and more particularly to improving the process of removing paper jams that occur on the transport path.
With an image forming apparatus, paper is transported on a transport path from a feeding portion to a discharge portion via an image forming portion, and images are formed by the image forming portion on the transported paper. There are image forming apparatuses that form a relatively long transport path spanning a plurality of internal locations, such as those having a feeding portion with a plurality of feed trays, or those with a transport path for inverting paper that has passed through the image forming portion and transporting the paper again to the image forming portion when forming images on both sides.
Meanwhile, there is a strong demand for speeding up the image forming process in image forming apparatuses. To this end, plural sheets of paper are fed continuously from the feeding portion at short intervals when the image forming process is performed continuously on a large quantity of paper.
With image forming apparatuses that perform fast image forming and have a relatively long transport path, the operation of the apparatus stops with a lot of paper on the transport path if a paper jam occurs in part of the transport path.
Removing all of the paper on the transport path during the jam removal operation makes the jam removal operation troublesome, and leads to resource wastage due to usable paper also being discarded.
In view of this, a conventional image forming apparatus disclosed in JP 2001-334736A detects jams on either of two transport paths from two feeding portions to the image forming portion, and displays on which of the two transport paths a jam has occurred.
However, while it is possible with the above conventional image forming apparatus to identify the location of jams that occur between the feeding portion and the image forming portion, it is not possible to identify the location of jams that occur between the image forming portion and the discharge portion. Also, consideration is not given to the removal of image-formed sheets from the transport path as a result of the jam removal operation.
The operator is thus unable to accurately identify paper that should be removed from between the image forming portion and the discharge portion on the transport path in the jam removal operation, giving rise to the possibility that the image forming process will be restarted with paper remaining that should have been removed or paper being eliminated that need not have been removed. As a result, it may not be possible to properly restart the image forming process or this may lead to resource wastage due to usable paper being discarded.
Also, when image-formed sheets are removed from the transport path as a result of the jam removal operation being performed during an image forming process for forming a plurality of page-numbered images on a plurality of sheets in page order, not all of the pages of images will in the ejected stack of image-formed sheets. The operator thus has to perform the image forming process again in relation to the missing pages after checking the stack of image-formed sheets, and insert the obtained image-formed sheets in a prescribed place in the stack of image-formed sheets initially ejected, creating more work for the operator.
A feature of the present invention is to identify and display paper that should be removed in a jam removal operation, based on the result of detecting the location of jammed paper and other paper on a transport path from a feeding portion to a discharge portion, and thereby ensure that only paper that should be removed is reliably removed.
Another object of the present invention is to perform image forming in relation to an image for facilitating the collation of stacks of image-formed sheets after the jam removal operation, and thereby facilitate the process of collating the stacks performed by the operator.